The trend in the circuit protection industry is currently toward complete circuit protection which is accomplished by the addition of supplemental protection apparatus to standard overcurrent protective devices, such as molded case circuit breakers. In the part, when such auxiliary protection apparatus or other circuit breaker accessories were combined with a standard circuit breaker, the accessories were usually custom-installed at the point of manufacture. The combined protective device, when later installed in the field, could not be externally accessed for inspection, replacement or repair without destroying the integrity of the circuit breaker interior. An example of one such factory installed circuit breaker accessory is found in U.S. Pat. No. 4,297,663 entitled "Circuit Breaker Accessories Packaged in a Standardized Molded Case", which Patent is incorporated herein for reference purposes.
A more recent example of a circuit breaker including additional accessories is found in U.S. Pat. No. 4,622,444 entitled "Circuit Breaker Housing and Attachment Box" which allows the accessories to be field-installed within the circuit breaker without interfering with the integrity of the circuit breaker internal components. This is accomplished by mounting the accessories within a recess formed in the circuit breaker enclosure cover.
An electronic trip actuator which is mounted within the circuit breaker enclosure is described within U.S. Pat. No. 4,679,019 entitled "Trip Actuator for Molded Case Circuit Breakers". The circuit breaker actuator responds to trip signals generated by an electronic trip unit completely contained within a semi-conductor chip such as that described within U.S. Pat. No. 4,589,052. The development of a combined trip actuator for both overcurrent protection as well as accessory function is found within U.S. Pat. No. 4,700,161 entitled "Combined Trip Unit and Accessory Module for Electronic Trip Circuit Breakers". The aforementioned U.S. Patents which represent the advanced state of the art of circuit protection devices are incorporated herein for reference purposes.
When the integrated protection unit is located remotely from the protected industrial equipment, it is important for the equipment operator to ascertain the status of the operating power supplied to the equipment. Should an overcurrent condition occur causing the circuit breaker to interrupt the equipment operating power, some means must be employed to provide immediate visual and audible indication to the equipment operator. One purpose of the instant invention is to provide a trip signal indicator unit to circuit breakers which is field-installable and which is capable of indicating the occurrence of a trip operation to a location remote from the circuit breaker.